In 1989, Letto sought election to the town council of Labrador City, and was elected. He was also re-elected to the council in 1993 and 1997. Then in 2001, Letto was elected as mayor of Labrador City. During the
2003 Newfoundland and Labrador general election, he ran in the provincial
riding of
Labrador West as the
Progressive Conservative candidate, but was defeated by
Randy Collins of the
NDP. On May 24, 2005, Letto ran for the
Conservative Party of Canada in the
Labrador riding in a by-election. Letto lost, but increased the Conservative vote in the traditional Liberal riding substantially. On September 27, 2005, Letto was re-elected mayor of Labrador City in the
2005 municipal election. He did not seek a third term during the
2009 municipal elections, and was succeeded by Janice Barnes. Letto received a Federation of Canadian Municipalities Roll of Honour Award in June 2014. In August 2015, Letto was nominated as the Liberal candidate in Labrador West for the
2015 provincial election. On November 30, 2015, Letto won the seat, defeating New Democrat and former Wabush Mayor Ron Barron and Progressive Conservative incumbent
Nick McGrath. On November 8, 2018, Letto was appointed Minister of Municipal Affairs and Environment. In the 2019 provincial election Letto was defeated by NDP candidate
Jordan Brown in a major upset. ==Electoral record==